Slides from the joined webinar of Novatec, Micronaut and Camunda, see https://micronaut.io/2021/02/25/webinar-micronaut-and-camunda/

1. Process Automation
Quick Intro
@berndruecker

2. Credit Card
Handling
Payment
REST
Order
Fulfillment
REST
DB
PaymentId Amount Status
1 100 $ Collected
2 125 $ Open
Reporting of
overdue payments
{script}
Fixing open
payments
Scheduler to
process open
payments
Damn it – we
need a date!
…to be continued…

3. Using a workflow engine instead
Workflow Engine
Scheduler
Durable State
Workflow Definitions
V1
V2
Workflow Engine:
Is stateful
Can wait
Can retry
Can escalate
Can compensate
Provides visibility

4. Execute Processes
One process instance gets started.
It is persisted in the workflow
engine and „walks“ through the
process model.
@PUT
retrievePayment() {
result = workflowEngine.
startProcessInstance('payment')
if (result.hasEnded())
return 'paymentSucceeded'
else
return 'paymentSucceeded'
}
Your code to provide
a RESTendpoint
Instance
Id
Process
Definition
Current
State
…
…-7454 payment „Charge
Credit
Card“
…
…-4571 payment „Charge
Credit
Card“
…
Process Instance Table
Durable state of
workflow engine
(e.g. via relational database)
Your glue code to
implement the RESTcall
@Task('chargeCreditCard')
chargeCreditCard() {
...
restClient.put(
'http://creditCards/charge/',
requestData)
}
Credit Card
Service
REST

5. Value Proposition of a Workflow Engine
Value of Visibility
Value of
long running
capabilities
Process
Orchestration
Business Transactions,
Sagas
Solving challenges
with remote communication
Integration Patterns
Graphical Programming
Effort of introducing
a workflow engine

6. Warning:
Contains Opinion
@berndruecker

7. mail@berndruecker.io
@berndruecker
http://berndruecker.io/
Bernd Ruecker
Co-founder and
Chief Technologist of
Camunda

8. Camunda
• Workflow engine & process automation platform
• Source-available & developer-friendly
• Supports ISO standard BPMN
• Mature tooling, widely adopted
• On-prem or managed in the cloud
• http://camunda.com/

9. Service
A
Microservices
@berndruecker
Monolith
Service
B
Service
C
C
B
A
D

10. Service
A
Autonomous Microservices
@berndruecker
Service
B
Service
C

11. The era of APIs
API
API
API
API
API
API
API
API
@berndruecker

12. The era of APIs
API
API
API
API
API
API
API
External Services
Standard Software
API
Functions
@berndruecker

13. Connecting the dots…
API
API
API
API
API
API
API
Microservices
External Services
Standard Software
API
Functions
@berndruecker

14. Example
Checkout
Payment
Inventory
Shipment
@berndruecker

15. Order
Placed
Payment
Received
Goods
Shipped
Notification
Event-driven & Reactive
@berndruecker
Checkout
Payment
Inventory
Shipment

16. But there is trouble in the event-driven land!
Event chains that
implement processes
Implementing
long running behavior

17. Peer-to-peer event chains
Checkout
Payment
Inventory
Shipment
Order
placed
Payment
received
Goods
shipped
Goods
fetched
@berndruecker

18. Order
Responsibilities
Checkout
Payment
Inventory
Shipment
Payment
received
Order
placed
Retrieve
payment
@berndruecker

19. Order
Checkout
Payment
Inventory
Shipment
Stateful orchestration
This orchestration
requires state
@berndruecker

20. Order
Checkout
Payment
Inventory
Shipment
@berndruecker

21. Glue code (e.g. Java)
https://github.com/berndruecker/flowing-
retail/blob/master/kafka/java/order-
zeebe/src/main/java/io/flowing/retail/kafka/or
der/flow/FetchGoodsAdapter.java

22. It is easy to change the process flow
@berndruecker

23. Order
Checkout
Payment
Inventory
Shipment
@berndruecker
The workflow is domain logic as part of the service
@berndruecker

24. Want to learn more?
https://ProcessAutomationBook.com/
Available as early release
Free 30 days trial available
Featuring code examples:

25. 26
Large Number of Use Cases
91.2 Billion
ANNUAL ACTIVITIES
3,000+
WORKFLOWS
83.9 Billion
ANNUAL ACTIVITIES
800+
WORKFLOWS

26. Summary
• Use a workflow engine to automate long running processes
• Orchestration helps to avoid chaos in microservice architectures
• The value proposition of a workflow engine includes visibility
And NOW you can leverage it together with Micronaut!

27. Thank you!
@berndruecker

28. mail@berndruecker.io
@berndruecker
https://berndruecker.io
https://medium.com/berndruecker
https://github.com/berndruecker
https://www.infoq.com/articles/events-
workflow-automation
Contact:
Slides:
Blog:
Code:
https://www.infoworld.com/article/3254777/
application-development/
3-common-pitfalls-of-microservices-
integrationand-how-to-avoid-them.html
https://thenewstack.io/5-workflow-automation-
use-cases-you-might-not-have-considered/